Evaporator system



S. BROWN.

EVAPORATOR SYSTEM.

APPucATloN FILED JAN. 26, 1920.

Patented Feb. 7, 1922.

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STE@ STATES raraur certes.

STANLEY BROWN, OF GARDEN CITY, NEW YORK, ASSIG-NOR T0 THE GRISCOMRUSSELL COMPANY, 0F NEW YORK, N. Y.,

A. CORPORATION OF DELAWARE.

EVAPORATOR SYSTEM.

Specication of Letters Patent.

Patented Feb. 7, 1922.

Application flledrJ'anuary 26, 1920. Serial No. 354,000.

To all whom t may oon/cem:

Be it known that I, STANLEY BROWN, a citizen of the United States'residing at Garden City, in the county of Nassau, State of New York,have invented certain new and useful Improvements in Evaporator Systems;and I do hereby declare the following to be a full, clear, and exactdescr1ption of the invention, such as will enable others skilledv in theart to which it appertains to make and use the same.

This invention relates to improvements 1n evaporator systems, andparticularly to a feed water heater whereby the heat usually lost in theblow-down of an evaporator plant may be conserved without the additionof costly auxiliary apparatus to the plant.

A further object of the invention is to provide an apparatus for heatingthe feed water of an evaporator plant in which the concentrated solutionconstituting the blow-down does not come in contact with any heattransferring surface which would be corroded or scaled by the solution.

In the accompanying drawing I have shown in Fig. l an evaporator layoutcontaining a feed water heater embodyin my invention, and in Fig. 2 aslight modification.

In the drawing, which is largely diagrammatic, 1 indicates the firstunit of the evaporator plnant, here shown as a double effect plant ofwhich the second unit 2 has its heating coils 3 connected to th'e vaporline 4. 'of the first unit.

The steam coils of the first effect will be connected to a suitablesource of live steam (not shown) and the drain from the heating coils ofboth effects will be led to the. hot Well of the plant or otherwisedisposed of.

In an apparatus of this kind it is frequently desirable to deliver thevapor from the apparatus at a comparatively high temperature,particularly where the apparatus isl used to supply the boiler make-upfor high pressure steam plants, and as the temperature of the vapordelivered from the last effect determines the temperature of theblow-down, there would be considerable heat lost were the blow-downdischarged directly as waste from the evaporator.

a feed pipe 7 at the desired water level in the evaporator, a trap 8being interposed in the line 7 to hold the first effect at the desiredoperating pressure which must of course be higher than the pressure ofthe second effect.

It is customary to heat the feed water by means of the .exhaust steamfrom the auxihary apparatus used in connection with thel plant, forinstance on shipboard, the steam used for the hoisting engines andsimilar purposes is used in the evaporator feed heater, and in carryingmy invention into effect. I use the exhaust steam through the auxlllarysteam line 12 for heating the raw Water which enters the evaporator feedheater through the pipe 14 and is fed to .the evaporator by the pump 6,a separator Aplants of this character, as usually operated,

the volume of feed is maintained at such point with relation to the rateof the evaporation in the plant that the overflow through the blow-downis a material portionof the feed for instance for sea-water operationthe blow-down will equal about onethird the volume of the feed, that is,thel blow-down is concentrated to three times the salinit of thenormal'sea water. This. amount of water at the high temperature of thevapor discharge represents a considerable vquantity of heat and ifdischarged directly as waste, would materially reduce the efficiency ofthe plant as a whole. In carryingout the invention of the presentapplication the' blow-down discharge pipe 9 leads to a trap 11 and fromthe chamber or vapor space .of the trap aLpipe 15 leads ao/the exhauststeam line 12 which is usually at about atmospheric pressure, therebyrelieving the pressure on the blow-down so thatthe extra heatrepresented by the tempera- `ture above 212 degrees will be convertedinto latent heat, producing a quantity of steam, the proportion of thesteam to .the water depending upon the temperature of .the blow-down.Thus, if the blow-down is at 50 lbs; gauge, the temperature equiyalentof which is 297 degrees F. for each" pound of water, there will be 297minus 212, or 85 B.T.U. of heat available for flash.

As the latent heat of vaporization at 212 degrees is 966 B.'l`.U. over9% of the blowdown will be vaporized and w1ll be available for heatingthe feed water.

There is no danger of causing impurities in the water by thisarrangement, for the reason that while the blow-down is loaded withimpurities, the vapor from 1t w1ll be comparatively clean and contain alower per cent of impurities than the raw water into which it isdelivered in the open heater 13. t

In Fig. 2 a different arrangement 1s shown for accomplishing the sameresult. Instead of using the trap 11 an S-bend 11 is 1nstalled in theblow-down pipe 9 and above the S-bend an upwardly inclined pipe 15 leadsto the exhaust steam line. The S-bend is long enouh to cause a backpressure in the blow-dnown pipe beyond the connection of the pipe 15lfor the flash to pass through the pipe 15 to the heater, so that onlyconcentrated dirty water at low temperature is thrown away.

A heat exchanger of ordinary construction cannot be economically usedfor conserving `the heat from the blow-down, for it would require anextensive heating surface to absorb any considerable per cent oftheheat, and in view of the extreme impurlties in the blow-down the heatingsurface would not be efficient and would require cleaning and repairs tosuch an extent as to largely offset the heat-saving effected by itsuse.. "With the apparatus shown in the drawing, the only addition to theordinary evaporator plant is the trap or S-bend which is of negligib-lecost and requires no upkeep whatsoever.

ln the accompanying drawings l have shown the evaporator units arrangedfor series feed, that is, all the raw water is fed to the first effectand all the blow-down is from the last effect which is at the lowesttemperature. When the several effects are connected for parallel feedwith a blowdown for each effect discharging into a common blow line aneven greater quantity of heat will be saved by the invention of thisapplication for the resulting temperature of the blow-down from all theeffects will obviously be higher than from the las-t effect alone.

l claim:

1. ln an evaporator system, the combination of a feed heater, anevaporating unit said solution in excess of that contained atatmospheric pressure.

8. ln an evaporator system, the combination of a feed heater, an'evaporating unit comprising means for discharging theconatmosphericboiling point of the solution, means for converting thesensible heat contained in said solution in excess of that contained atatmospheric pressure into latent heat of vaporization at atmosphericpressure, and means for utilizing the vapor thus formed in said feedheater.

4. ln an evaporator system, the combination of a feed heater having anindependent source of vapor for heating the same, an evaporating unitcomprising means for discharging the concentrated solution at atemperature above atmospheric boiling point of the solution beingevaporated and means for utilizing in said feed heater the sensible heatcontained in said discharged solution in excess of that contained atatmospheric press-ure.

5. In an evaporator system, the combination of a feed heater, anevaporating unit comprising means for discharging the concentratedsolution at a temperature higher than the vaporizing temperaturecorresponding to the pressure in said heater, and means for utilizing insaid heater the excess of sensible heat conta-ined in said dischargedsolution above that contained at the pressure in said heater.

6. In an evaporator system, `the combination. of a feed heater, anevaporating unit comprising means for discharging the con.

centrated solution at a temperature higher than the vaporizingtemperature corresponding to the pressure in said heater, means forconverting the excess of sensible heat contained in said dischargedsolution above that contained at the pressure in said heater into latentheat of vaporization at the pressure of said heater, and means forcondensing the vapor thus formed in the feed heater.

lin testimony whereof l' affix my si nature.

. STANLEY BR WN.

vcent-rated solution at a temperature above

